Steering System

Because the Steering Gear is a very complex and and equally misunderstood component of the steering system, it commonly gets blamed for problems in drive ability when the fault may be elsewhere. To assist you in correct diagnosis of your steering system, here are some good steps to follow.Drive the Vehicle
If possible, drive the vehicle and verify the type and extent of the steering problem. If you are unable to duplicate the steering complaint, ride with the driver and observe the nature of the problem. Notice the point at which the problem occurs and it’s nature. Provide preventive maintenance services on the steering components, grease and re-torque and drive it again.Listen to the Driver
In every case, the driver will be able to tell you more about the steering difficulty than you can know. Is the system warm or cold? Is the vehicle always empty or loaded when the problem occurs? Does it only occur with one driver? Does the problem disappear only at low RPM conditions? Does the problem only appear after slowing down from highway speeds and then go away? Does the problem only appear turning in one direction? Does the problem only appear in one spot in the turn of the steering wheel?Give the Vehicle a Visual Inspection
Look for signs of vehicle abuse. Inspect the tires for previous impacts and side scuffs. It is easy to see an operator that takes pride in a piece of equipment and keeps it in good condition as well as equally easy to see a poorly maintained and abused piece of equipment.

Check the fluid first
Many factors contribute to looseness in the steering system. This looseness may be caused by something as simple as the fluid levels not being maintained at the recommended levels. Air entrapment may cause delayed action and/or over-reaction in the steering system. Oil foaming, fluid color and a burnt smell are all signs of problems related to the pump. As a pump degrades, chrome plating will flow through the system; this will usually be observed as a shine quality or reflective quality in the oil. Although water may be hard to spot, usually by draining a quart or better, water can be seen if present. Water, when heated, will react like air entrapment and degrade the overall system performance. Many vehicles can be found with old engine oil in their power steering systems. The suspended fuels, acids, carbon and sludge found in used engine oil quickly cause power steering hoses to break down.

Look at the Tires
Under-inflation of a vehicle’s tires can cause high steering effort, road wander and poor recovery. Improperly mounted or unbalanced tires can cause shimmy and excessive fluid heat. The presence of tire cupping and abnormal wear are all signs of alignment problems and troubleshooting should begin after the front end alignment has been checked.

Examine the Front End Components
Excess wear can cause road wander, high steering effort as well as shimmy and over-steering. Tie rod ends, drag links, idler arms, pitman arms, king pins, ball joints, steering arms, ubolts, and steering columns, each with a little wear, all add up to a lot of potential wear and road wander. Correct preventative maintenance with inspection and lubrication will extend the life of steering components.

Watch the front end Articulate
Sometimes the best way to look for looseness in a steering system is to securely block the rear end from moving and to start the engine and cycle the steering from right to left. Have the driver provide feedback as he turns and look for over motion, looseness and binding. Try this first loaded, then unloaded, as well as with the front end completely off the ground. The same smooth movement should be present under all loads. Watch the steering column, looking for smoothness and a lack of jerky movements. Remember, the vehicle linkage and engine can pose a great amount of danger to life and limb, so exercise care.

Truck? Inspect the Frame and Cab
Car? Inspect the Steering gear to frame connection
As the front end linkage turns, forces are applied to the frame laterally. The frame relies on the cross members to stabilize it through the turning movements with little to no frame flex allowed. A little known fact is that many Class 7 and 8 vehicle manufacturers rely on the front bumper as the vehicle’s front cross member. After market bumpers as well as broken, removed and loose bumpers can contribute to road wander as well as shimmy. As the steering gear turns under load, see that the steering box is tightly bolted to the frame and no movements between the two are seen. Since, on many steering gear models, the gear requires a slip joint on the steering column for the valve to shift, loss of motion in the steering column can force the valve to react erratically. In more severe circumstances, cab mounts can crack and break, allowing the cab to sit down on the steering gear. This by itself can cause any number of steering difficulties.

Inspect the Hydraulic System
Look at the steering gear, hoses, valves, cylinders and the pump. The hoses should be reasonably flexible, the painted components will discolor and hoses become stiff, due to heat. Under operation, the pump, when power steering is applied, will draw down the engine RPM if properly operating. Control valves on linkage systems need to be free to operate smoothly without sudden motion as well as be reasonably clean. Dirt acts like an abrasive when allowed to enter a steering system and degrades smooth movement. For steering systems to operate correctly, they need proper pressure, measured in pounds per inch, and proper delivery, measured in gallons per hour. A pump may be able to pump to twelve hundred pounds pressure, but not be able deliver the flow to operate a steering gear. Conversely, a pump may be able to pump eight gallons per hour, but not exceed one hundred pounds. Steering pressure and flow requirements are determined by the size of the vehicle and intended weight capacity. Consult the vehicle manufacturer or steering gear manufacturer for minimum acceptable standards.

Back to the Front End Components
Perform ALL wear tests as recommended by the vehicle manufacturer. This should include the King Pins, Tie Rod Ends, Axle Spindles as well as all other front end components. Articulate the front end by hand with the pitman arm removed from the steering gear. The front end should articulate freely without binds and noticeable noises. Set the front wheel bearings with a torque wrench as recommended by the vehicle manufacturer. Check for excessive movement in the springs, hangers and other attaching parts.

Inspect the Rear of the Vehicle
A poorly attached body will allow the frame to flex and wear frame cross members. A loose rear suspension will cause the front end to appear loose (rear steer).

Steering Gear
The steering gear should now be considered as a potential problem. Lash adjustments can be checked against factory standards and if the gears exceeds those standards, repair or replacement is necessary. In order to insure a safe steering system, follow these guidelines.

Many factors influence steering gear troubleshooting.
Here is a list of common complaints and their usual cause.

Road Wander
• Tire Pressure incorrect or unequal
• Components in steering linkage loose or worn.
• Wheel bearings improperly adjusted or worn.
• Front end alignment out of specification.
• Dry fifth wheel or poor finish on fifth wheel or trailer plate.
• Steering gear mounting loose on frame.
• Looseness in rear axle assemblies.
No Recovery
• Low tire Pressure
• Front end component bind.
• Front alignment incorrect.
• Tight front axle king pins.
• Dry fifth wheel or poor finish on fifth wheel or trailer plate.
• Steering gear improperly adjusted
• Steering gear bearings worn.
Shimmy
• Badly worn or unevenly worn tires
• Improperly mounted tire or wheel
• Wheel bearings improperly adjusted or worn
• Components in steering linkage loose or worn
• Wheel or braked drums out of balance.
• Front end alignment incorrect.
• Air in hydraulic system.
Over-steering/Darting
• Dry fifth wheel or poor finish on fifth wheel or trailer plate.
• Components in steering linkage loose or worn
• Steering Column binding
• Steering gear improperly adjusted
• Steering gear bearings worn.
• Rear axle mounts (rear steer)
High Steering effort in one direction
• Unequal tire pressure
• Vehicle overloaded
• Inadequate hydraulic system performance
• Excessive internal leakage in one direction.
• Bad/worn steering gear valve.
High Steering Effort in both directions
• Low Tire Pressure
• Vehicle Overloaded
• Low Hydraulic Fluid Level
• Insufficient Pump pressure and flow
• Component bind in steering system
• Restriction in return line
• Excessive internal leakage
• Oversize tires
Lost motion at steering wheel
• Steering Column loose on shaft
• Loose connection between the steering gear, intermediate column and steering column
• Steering gear loose on frame
• Pitman arm to shaft looseness
• Steering Component wear.
• Steering Gear incorrectly adjusted.
Excessive Heat
• Excessive Pump Flow
• Vehicle overloaded
• Undersized steering hoses
• Restriction in oil delivery system.
• Steering gear valve worn/failed
• Column bind
• Pop-off’s not adjusted properly

The following represents some common sense guidelines for the maintenance of steering systems. Although most are well known, each deserves a repeat.

1. Do not remove a steering gear cover and replace it with the gear installed in the vehicle. Dirt introduced into a steering system can cause  serious problems.
2. Never adjust a steering gear while either shaft is connected to the linkage. The readings you get will not be true.
3. Always re-seal a steering gear in a clean environment.
4. Always have a trained rebuilder perform internal adjustments.
5. Always flow test a steering gear prior to installation verifying the operation of pressure relief, pop off valves, and steering control valve.
6. Never rebuild a steering gear involved in a collision where the front axle was affected. Most shafts, unless completely broken, will not exhibit any outward signs of problems, even when present.
7. Never install or remove a pitman arm with a hammer!
8. Always use the fluid recommended by the manufacturer, or if unknown, consult a rebuilder for information.
9. Always perform preventative maintenance functions on the steering system. Change fluids and filters within the manufacturer’s guidelines. Systems without filters should have them, systems without coolers should consider them.

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